Confused by multiple CdA results
Posted: Thu May 16, 2019 6:00 am
While trying to analyze some data I realized that Isaac is offering me THREE different CdA results for the same data.
I recorded a ride in Profile 4 using my Aeropod and the bike's DFPM. I edited the activity to remove everything except for 3 laps of a loop. The loop was not ideal because it required slowing for a couple of turns but I rode the entire time without touching the brakes and without changing position on my TT bike, though I did have to turn my head a bit to look for traffic when I coasted up to the turns.
CdA estimate #1 is calculated by Isaac for the entire ride: 0.244
CdA estimate #2 is from CdA Analysis. I selected the entire ride as shown on the screen shot: 0.277
CdA estimate #3 is from the HR data, 4*HRavg/1000=0.214
That's a fairly diverse group of numbers.
Why is there so much difference? And which is more credible?
I recorded a ride in Profile 4 using my Aeropod and the bike's DFPM. I edited the activity to remove everything except for 3 laps of a loop. The loop was not ideal because it required slowing for a couple of turns but I rode the entire time without touching the brakes and without changing position on my TT bike, though I did have to turn my head a bit to look for traffic when I coasted up to the turns.
CdA estimate #1 is calculated by Isaac for the entire ride: 0.244
CdA estimate #2 is from CdA Analysis. I selected the entire ride as shown on the screen shot: 0.277
CdA estimate #3 is from the HR data, 4*HRavg/1000=0.214
That's a fairly diverse group of numbers.
Why is there so much difference? And which is more credible?